tibbetts



June 12, 1923. r 1,458,204

R. w. TIBBETTS PUMP Original Filed Nov. 2, 1920.

Patented June 12, 1923.

UITED' STTES PATENT OFFICE.

RAYMOND W. TIBBETTS, OF ROXBUBY, MASSACHUSETTS.

PUMP.

Application filed November 2, 1820, Serial No. 421,282. Renewed April 17, 1923.

To (1 whom it may concern Be it known that I, RAYM ND W. Treen'r'rs,

a citizen ofthe United States, residing at compressing the refrigerant, in which rotors of the intermeshlng herring bone gear. type are used, a small quantity of the oil will be trapped by the intermeshing teeth which results in pressing the gears apart and in the hard running of the pump, This condition ensues because the rotation of the gears is in a direction that causes the liquid to be forced or squeezed progressively from the outside edges of the gears inward towards the apexes of the VS formed by the teeth of the gears, a closed pocket being produced just before the complete entrance. of the tooth of one gear into the tooth-space of the other gear, the result being as stated, the trapping of a small bit of liquid. The object of this invention is to remedy the condition just described and to do so by means at once simple and not impairing the efficiency of the pump. The invention therefore consists in the pump having the con. struction and relation of parts defined by or embraced within the language of the appended claims.

In the accompanying drawings;

Fig. 1 is a vertical section thru the pump mechanism of a refrigerating apparatus embodying the invention;

- Fig. 2 is a vertical section on the line 22, of Fig. 1. I

In the embodiment of the invention shown in the drawings, there is a gear case, 10, bored with two cylindrical openings, 11, that open into each other at one side in which are respectively mounted for revolution, inter meshing herring bone gears, 12, one of which is fixed to a shaft, 13, that receives power from a suitable motor, not shown. At one end the gear chambers are closed by a wall which is bolted to the casing, 10, and at the other end by an integral wall, 1 1, which lies adjacent to the wall, 15, of the chamber of the refrigerating apparatus in which the pump is located. Directly below the point where the two gears intermesh is to the accompanying a horizontal port, 16, which alines with the hole, 17 in the wall, 141, thru whichthe gas to be compressed enters the port, 16,'and is taken up by the revolving gears.

Above the intermeshing gears is a tank or reservoir, 18, containing oil or other liquid, suitable for sealing and lubrication, from which at or, near the end of the gears two ports, 19, lead downward into the gear chambers and thus the liquid flows from the tank to the gears. Situated between said two ports and extending upwardly from the gears at their longitudinal center is a port, 20, that is prolonged so that it opens into the tank, 18, at or near the top thereof, and into such port and driven upward therethru, is forced the'mingled gas and liquid, separa tion of the oil and gas taking place in the upper part of the tank, 18, above the normal liquid level therein.

The gears rotate in the'direction of the arrows applied thereto in Fig. 1, and their teeth are so arranged that they mesh at the outside edges of the gears so that a tooth on one gear enters the tooth-space of the opposite gear and oil will be pushed or forced along such space toward the apexes of the intermeshing teeth and finally moved up into the outlet port. y Between each pair of sections forming each gear is a washer, 21, of a diameter to fill the gear case, and the two washers, at

adjacent sides, are flattened and in contact so that each .restrains the other from rotating. Thus the washers do not "rotate with the gears. In the sides of the two washers wherethey adjoin are notches, or recesses, 22, that are in communication with the teeth spaces of the gears just before and at the time of completion of intermeshing of teeth of one gear and spaces of the other gear,

which recesses, 22, open into the lower end of the port, 20, and thus liquid trapped in such teeth spaces may escape at the ends thereof into such recesses, 22, and flow out into the port, 20. and thereby the objectionable consequences of trapping the liquid in the teeth spaces avoided. As shown in the drawing one of the gears where the two abut has a hub or flange, 23, which enters the openingin the washer which hub or flange abuts against the adjacent end of the other gear.

It is to be understood that while the invention is especially advantageous as a part of refrigerating apparatus, its use is not limited to that connection. The term gas inoludesany aerit'onn liquid with. which the pump may deal.

l Vhat I claim is;

l. A pump having rotors consisting of intermeshing herring bone 'ears and passages at the central part or' the gears for the escapeot liquid from the pocket formed by the intermeshing of the gear teeth, said passages opening into the spaces between the gear teeth and an outlet pipe to which liquid is directly delivered, said passages being merely relief ports.

2. A pump having rotors consisting of intermeshing herring bone gears with means at the central part of the gears for the escape of liquid from the pocket formed by the intermeshing of the gear teeth said means being passages 111 non-rotating Washers between adjacent sections. of said gears, said 20 Washers being placed edge to edge With flat abutting surfaces.

3. A pump having rotors consisting of intermeshing gears and passages situated intermediate the outer ends of the gears and leading from a point Where opposing gear teeth mesh to an outlet and an outlet pipe to Which liquid is directly delivered, said passages being merely relief ports In testimony whereof I hereunto afi'ix my signature.

RAYBLIOND W. TIBBETTS, 

